35 Coding Interview Questions (With Sample Answers)
Updated 20 June 2023
Coding is a useful skill that many software developers regularly use to translate their instructions into a format that computers can process and use. If you're interviewing for a software developer position, you're likely to encounter interview questions about coding. Understanding how to answer these questions effectively can increase your chances of getting a job offer. In this article, we list 35 common coding interview questions you might encounter and provide sample answers to some of them to help you prepare for your interview.
Please note that none of the companies, institutions or organisations mentioned in this article are affiliated with Indeed.
10 general coding interview questions
Here are some general coding interview questions that an interviewer might ask at the beginning of the interview to learn more about your personality and characteristics:
Tell me more about yourself.
What do you enjoy most about coding?
What programming languages are you familiar with?
What are your strengths and weaknesses?
How did you hear about this company, and why do you want to work here?
What interests you about this job?
What are your career goals?
How do you handle working in a high-pressure environment?
What skills do you think are useful for a software developer?
Why are you leaving your current position?
10 questions about experience and background
Here are some questions that an interviewer might ask to learn about your experience and background in coding:
Where did you learn how to code?
Do you have any professional certifications or qualifications in coding?
Tell me about a time when you had to explain a programming concept to someone without a technical background.
Tell me about a project you worked on and describe how you contributed to it.
How many years of experience do you have in coding?
Tell me about a time when you collaborated with a team of developers on a coding project.
Tell me about a time when you mentored a junior software developer.
Tell me about a time when you worked with limited documentation or resources.
Tell me about a challenging programming problem that you resolved and explain how you did so.
Tell me about a bug that you identified in your code and share how you rectified it.
10 in-depth questions
Here are some in-depth questions that an interviewer might ask to test your coding skills and determine whether you're a suitable candidate for the position:
What's the difference between a binary search tree and a balanced binary search tree?
Explain the difference between a GET and POST request.
How do you find the longest common prefix in a string array?
How do you find common elements in two different arrays?
Explain how you might implement a binary search algorithm.
How would you implement a Trie data structure for efficient prefix searching?
What are the steps for implementing a maximum subarray problem algorithm?
What are the steps for implementing a heap data structure?
What's your understanding of how a cache works?
What's an AVL tree?
5 interview questions with sample answers
Preparing some sample answers before your interview can enable you to provide more thoughtful answers, especially to common questions. Here are some coding interview questions with explanations of how to answer them and sample responses:
1. Which programming language do you prefer?
The hiring manager may want to assess your proficiency in specific programming languages. Choose a programming language that you're familiar with and can explain well and try to mention one that the employer listed in the job advertisement. If you're familiar with multiple languages, it may be beneficial to choose a dynamic language instead of an older one such as HTML.
Example: 'Although different languages are suitable for certain projects, I like Python for solving algorithmic problems. I find that it's simple to use and has beneficial features. After my experience with it at Global Solutions, I wanted to develop my Python understanding further, so I designed and developed a software application for a mobile game to practise speaking elements while learning a new language. I have a strong understanding of Python based on my professional and personal experience'.
2. What's your process for rectifying a crashing program?
The hiring manager may ask this question to determine your skills and experience in resolving this issue. Answer by sharing a previous experience of how you used your hard and soft skills to find a resolution. Describe how you search for bugs and the steps you take to resolve them. Carefully explain your process to the interviewer in a logical way to show you thoroughly understand the process.
Example: 'I worked at a startup called Innotech after graduating from university. I enjoyed the projects I worked on there, but we frequently had problems with crashing programs. To resolve this, I developed a method for finding bugs. After running a debugger, I look for patterns. For example, the program crashes while running certain commands or in specific conditions. If the program only crashes every fifth time the page loads, I investigate that further. Once I identify patterns, I consider problem areas that might include elements of those patterns and use a code to search for them'.
3. How would you handle working in a team with people from other departments?
Interviewers might ask this question to determine whether you can work with other developers effectively. Use this opportunity to provide examples of your interpersonal and communication skills. Consider sharing examples of how you've used these skills in the past to achieve success at work.
Example: 'I work well in teams, including ones with non-tech members. I find that these groups can produce products and solutions that a team of like-minded people may not consider. I also enjoy meeting new people and considering other perspectives on the projects. I've worked in mixed teams and teams with only programmers, and I feel the mixed groups were often more innovative. I'd welcome an opportunity to work on this type of team'.
4. What happens after you type in a website's URL?
This is an example of an in-depth question that an interviewer may ask to test your knowledge of a technical aspect of coding. Ensure that your answer is detailed and concise to demonstrate your expertise. It may be beneficial to prepare responses to technical questions such as these in advance to ensure that you don't miss any details.
Example: 'After typing a URL into a browser, the browser checks the DNS record and cache to find the corresponding IP address. Then, the browser may check the operating system cache, the router cache and the ISP cache. The ISP's DNS server then initiates a DNS query to find the IP address of the server that hosts the site, and the browser initiates a TCP connection with the server. Finally, the browser sends an HTTP request to the web server, the server sends a response and the browser displays the HTML content'.
5. How do you keep your technical industry knowledge current?
The programming field is constantly evolving, and interviewers may ask this question to determine whether you can adapt quickly. When answering this question, highlight that you enjoy learning new elements and coding languages. You can also share examples of learning opportunities that you intend to pursue.
Example: 'I enjoy keeping my programming knowledge current and learning new languages. I regularly listen to programming podcasts and participate in online communities with other programmers. I also find that online courses are helpful for learning new skills. While I was learning Python, I used podcasts and online courses to study the language while working on a project'.
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